Recently, an adaptive modulation and coding (AMC) scheme and an auto repeat request (ARQ) or a hybrid auto repeat request (HARQ) scheme are generally used in a mobile communication system in order to enhance a throughput so that an efficient communication can be performed.
In the AMC scheme, a modulation and a channel coding manner in a transmitting side are changed in accordance with a channel status when the transmitting side transmits data to a receiving side. The transmitting side can find the channel status by itself, but in general the receiving side measures the channel status and informs the transmitting side of the result so that the transmitting side obtains channel status information. The channel status information can be called channel quality information.
In the ARQ or HARQ scheme, the receiving side informs the transmitting side whether data received from the transmitting side has an error or not and the transmitting side retransmits data when the received data has an error. Namely, when receiving data from the transmitting side without an error, the receiving side transmits an ACK to the transmitting side and when receiving data from the transmitting side with an error, the receiving side transmits a NACK to the transmitting side so that the transmitting side retransmits the data.
In the AMC scheme or the ARQ or HARQ scheme, it is necessary for the receiving side to transmit feedback information such as channel quality information and ACK/NACK to the transmitting side. In this case, the receiving side needs radio resources for transmitting the feedback information to the transmitting side. Since the radio resources for transmitting the feedback information such as channel quality information or ACK/NACK, etc are statically allocated to the receiving side in the code division multiple access (CDMA) communication system, the radio resources once allocated to the receiving side cannot be used for other purposes although it is unnecessary for the feedback information to be transmitted, so that total radio resources are wasted.